Numerous areas of biochemical, biophysical and medical research depend upon measurements of time-resolved fluorescence and more recently, of time-dependent photon migration in tissues. In recent years these phenomenan have been studied by the technique of frequency-domain fluorometry (FREDOF), which provides good signal-to-noise, ease of use, and good resolution of complex decays. However, the time-resolution of FREDOF is currently limited by the use of electro-optic (E-O) devices which allow light modulation to only 200 MHz with approximately 5 percent transmission. The long range goal of this program is to circumvent these frequency and transmission limitations by the use of advanced acousto-optic technology of which Brimrose is a high frequency MHz-GHz Acousto-Optic manufacturer. As a Phase I goal it is proposed to fabricate the acousto-optic modulators with a light-modulation bandwidth of DC to 200 MHz, with at least 50 percent of the light in the modulated beam. Additionally, these devices will provide transmission from 200-1000nm, so as to allow its use in diverse studies ranging from intrinsic DNA and protein luminescence (250-300nm) to studies of NIR dyes for clinical sensing (600-800nm). The devices will be designed for use with laser sources, such as the CW argon ion laser (275nm). These devices will be tested and evaluated at the University of Maryland Medical School, Center for Fluorescence Spectroscopy.